PATHOPHYS: ARDS Flashcards
What is ARDS?
Severe, acute lung injury involving diffuse alveolar damage, increased microvascular permeability, and non-cardiogenic pulmonary edema
Is the hypoxemia associated with ARDS refractory or responsive to oxygen?
refractory!
List the 4 criteria for diagnosis of ARDS.
1) Acute onset of respiratory failure
2) Bilateral infiltrates on chest x-ray
3) No evidence of volume overload (not cardiogenic)
4) PaO2/FiO2 < 300
What is the mechanism of lung injury in ARDS?
1) activation of inflammatory mediators and cellular components
2) ddamage to caillary endothelial and alveolar epithelial cells (type I pneumocytes especially vulnerable)
3) Increased permeability (to water and protein) of the alveolar capillary membrane
4) Influx of protein rich edema fluid and inflammatory cells into air spaces
5) surfactant dysfunction
What is the major DIRECT cause of ARDS?
Pneumonia/aspiration of gastric contents
What is the major INDIRECT cause of ARDS?
Sepsis
What are the stages of ARDS?
1) Exudative (acute) phase (0-4 days)
2) Proliferative phase (4-8 days)
3) Fibrotic phase (>8 days)
4) Recovery
In what stage of ARDS does repair begin?
TRICK QUESTION: repair begins as soon as inflammation begins
What are the 4 major factors that increase risk of death from ARDS?
1) chronic liver diseaase
2) non-pulmonary organ dysfunction
3) sepsis
4) advanced age
The lung-injury score is based on what 4 factors?
1) chest X-ray
2) PaO2/FiO2
3) PEEP
4) Respiratory compliance
What is PEEP?
positive end-expiratory pressure (pressure used to recruit atelectatic alveoli and increase FRC–like dog sticking face out of window)
What natural part of expiration will cause PEEP?
closure of vocal cords
Does ARDS increase or decrease compliance?
DECREASE!
A significant reduction in mortality in patients with ARDS was achieved by doing what?
deploying a lower tidal volume than usual
When would you expect to see a pneumothorax in a patient with ARDS?
after two weeks of ARDS onset
